fix(cli): harden skin yaml parsing for invalid section types

hermes_cli/skin_engine.py

@@ -666,25 +666,46 @@ def _load_skin_from_yaml(path: Path) -> Optional[Dict[str, Any]]:
     return None
 
 
+def _mapping_or_empty(value: Any, *, section: str, skin_name: str) -> Dict[str, Any]:
+    """Return a mapping value or an empty dict when the section type is invalid."""
+    if isinstance(value, dict):
+        return value
+    if value is None:
+        return {}
+    logger.warning(
+        "Skin '%s' has invalid '%s' section type (%s); ignoring section",
+        skin_name,
+        section,
+        type(value).__name__,
+    )
+    return {}
+
+
 def _build_skin_config(data: Dict[str, Any]) -> SkinConfig:
     """Build a SkinConfig from a raw dict (built-in or loaded from YAML)."""
     # Start with default values as base for missing keys
     default = _BUILTIN_SKINS["default"]
+    skin_name = str(data.get("name", "unknown"))
+    color_overrides = _mapping_or_empty(data.get("colors"), section="colors", skin_name=skin_name)
+    spinner_overrides = _mapping_or_empty(data.get("spinner"), section="spinner", skin_name=skin_name)
+    branding_overrides = _mapping_or_empty(data.get("branding"), section="branding", skin_name=skin_name)
+    emoji_overrides = _mapping_or_empty(data.get("tool_emojis"), section="tool_emojis", skin_name=skin_name)
+
     colors = dict(default.get("colors", {}))
-    colors.update(data.get("colors", {}))
+    colors.update(color_overrides)
     spinner = dict(default.get("spinner", {}))
-    spinner.update(data.get("spinner", {}))
+    spinner.update(spinner_overrides)
     branding = dict(default.get("branding", {}))
-    branding.update(data.get("branding", {}))
+    branding.update(branding_overrides)
 
     return SkinConfig(
-        name=data.get("name", "unknown"),
+        name=skin_name,
         description=data.get("description", ""),
         colors=colors,
         spinner=spinner,
         branding=branding,
         tool_prefix=data.get("tool_prefix", default.get("tool_prefix", "┊")),
-        tool_emojis=data.get("tool_emojis", {}),
+        tool_emojis=emoji_overrides,
         banner_logo=data.get("banner_logo", ""),
         banner_hero=data.get("banner_hero", ""),
     )

tests/hermes_cli/test_skin_engine.py

@@ -199,6 +199,37 @@ class TestUserSkins:
         # Should inherit defaults for unspecified colors
         assert skin.get_color("banner_border") == "#CD7F32"  # from default
 
+    def test_load_user_skin_invalid_section_types_fall_back_to_defaults(self, tmp_path, monkeypatch):
+        from hermes_cli.skin_engine import load_skin
+
+        skins_dir = tmp_path / "skins"
+        skins_dir.mkdir()
+        import yaml
+
+        (skins_dir / "broken.yaml").write_text(
+            yaml.dump(
+                {
+                    "name": "broken",
+                    "colors": ["not", "a", "mapping"],
+                    "spinner": "invalid",
+                    "branding": ["also", "invalid"],
+                    "tool_emojis": ["invalid"],
+                    "tool_prefix": "!",
+                }
+            ),
+            encoding="utf-8",
+        )
+        monkeypatch.setattr("hermes_cli.skin_engine._skins_dir", lambda: skins_dir)
+
+        skin = load_skin("broken")
+
+        assert skin.name == "broken"
+        assert skin.get_color("banner_title") == "#FFD700"
+        assert skin.get_branding("agent_name") == "Hermes Agent"
+        assert skin.get_spinner_list("waiting_faces") == []
+        assert skin.tool_emojis == {}
+        assert skin.tool_prefix == "!"
+
     def test_list_skins_includes_user_skins(self, tmp_path, monkeypatch):
         from hermes_cli.skin_engine import list_skins
         skins_dir = tmp_path / "skins"